I've read that you need to look at the ratio of EPA to DPA, usually about 1.5:1...these are 2 essential fatty acids. Needs can also vary according to age. There is also a minimum combined amount to look for...I've seen in the region of 600mg.
This article might be helpful. All the charts I found seemed to be connected to specific brands. And there are studies if you are so inclined.
I take this...you can compare it to Equazen. Usually just one a day.
Amazon.co.uk User Recommendation
https://www.healthline.com/nutrition/fish-oil-dosage